Notice the warning about the number of Smolyak nodes: The number of nodes for each dimension must be n = 2^k+1 for some positive integer k. If user calls the constructor with different number of nodes, the constructor increases n to the next admissible value (from 80 to 129 for capital, and from 50 to 65 for labor).

Notice that the residuals in Smolyak and tensor bases are of similar magnitude, despite the fact that Smolyak is using around half the number of nodes and bases functions (i.e., its interpolation matrix is around one-forth the size of the tensor interpolating matrix).